The objective of this research is to develop the principles of continuum mechanics for the living systems, and to determine their constitutive equations, so that biophysical problems can be analyzed with precision. In the past three years we have developed the uniaxial constitutive relations for the mesenteric connective tissues, the aorta, the thoracic and mesenteric arteries, the papillary muscles, and the ureter. Concomittant theoretical analyses were made for red blood cells, capillary blood flow, pulmonary microcirculation, and ureteral peristalsis. In addition, a new method of "super-resolution" of interferometric photomicrographs was developed so that dimensions can be resolved in the living state under an optical microscope to 1/10 of the wave length of light. With this background, we wish to continue this research to: (1) Extend the constitutive equations to three-dimensional states of stress and strain, and to a broader range of connective tissues, blood vessels, heart muscles, and smooth muscles. (2) Analyze microcirculation with greater attention to the interaction of red blood cells and the endothelial wall, and fluid transport in the tissue space outside the capillary blood vessel. (3) Study the structure of the lung, use the constitutive equations of the structural components and the geometric data to deduce the elasticity of the lung tissue. This includes a detailed study of the mechanics of surfactants. (4) A similar analysis of the heart, based on the active and passive characteristics of the heart muscle and the architectural data of the heart. Develop a rational mechanics of the heart and the lung.